Dewatering or drying of peat



Sept. 4, 1951 D. 5. KING 2,566,943

DEWATERING OR DRYING OF FEAT Filed Oct. 29, 1947 2 Sheets-Sheet 1 P 1951 D. 5. KING 2,566,943

DEWATERING OR DRYING OF FEAT Filed Oct. 29, 1947 2 Sheets-Sheet 2 Patented Sept. 4, 1951 I 2,566,943 DEWATERING OR DRYING F PEA'I.

Dudley Seaton King, London, England Application October 29, 1947, Serial No. 782,867 In Great Britain September 30, 1946 1 Claim. (01. 34-412) This invention relates to the de=watering or drying of peat.

As is well known, newly cut peat contains from 80% to 90% by weight of water and the elimination of this water is a difflcult problem. Air dryingis the method most commonly used. This is quite effective, but it takes a long time to complete and requires a great deal of space. Moreover, the condition of the finally produced prod not depends upon atmospheric conditions.

The removal Of the water by heating is uneconomic because of the size of the installations required and also because of the very large amount of heat which is consumed. Attempts have also been made to remove the water in presses but the plant required is very expensive, a very large amount of power has to be used and the degree of dehydration which is achieved is disappointing.

According to the invention, the peat to be dewatered is extruded to a ribbon shape and the ribbon is compressed between two moving surfaces which reduce its thickness.

The apparatus in accordance with the invention can be of a simple form, comprising essentially an extruder having a fish-tail discharge nozzle arranged with its longer axis horizontal and a pair of horizontal rollers arranged one above the other.

A certain amount of water will be squeezed out of the peat during the extrusion and the barrel of the extruder can therefore, be provided with holes for evacuation of this water. The primary object of the extruder is however, not to effect the dewatering but to prepare the peat for presentation to the rollers.

It is, of course, important that the water which is removed from the peat by the rollers should not be allowed to come into contact again with the de-watered peat. This can be ensured by causing the ribbon of peat which leaves the extruder to travel slightly upwards to the nip of the rollers and to continue to travel upwards after passing through the nip. In the preferred form of apparatus in accordance with the invention, this upward path is contrived by setting the upper roller a little nearer the extruder than is the lower roller.

The use Of large diameter rollers ensures that the squeezing of the ribbon is applied gradually and relaxed gradually. Rollers of about 24 inches diameter give very good results.

The rollers can also serve to remove water from the peat by the application of heat. In

that case, it is, of course, of advantage to keepthe peat in contact with a heated roller as long as possible. In the preferred form of the invention, the upper roller is steam heated and maintained at a higher temperature than the lower roller. This helps to keep the peat in contact with the upper roller after it has passed the nip 0f the rollers. It is also advantageous in this connection to provide the upper roller with a roughened surface.

In order that the invention may be thoroughly understood and be more readily carried into effect, examples of a machine in accordance with it will now be described with reference to the accompanying drawings in which:

Figure 1 is a semi-diagrammatic side elevation of the preferred form of machine.

Figure 2 is aplan view of the machine shown in Figure l and Figure 3 is a side elevation of a modified form of machine.

The machine shown in Figure 1 comprises a frame It] on which is mounted a roller l2 in bearings M. The frame also supports a lower roller 16 which is carried by pivotally mounted arms I8 and is urged into contact with the upper roller l2 by a spring 20. The lower roller is driven by means not shown through a belt 22.

A second frame 24 is provided which supports a pair of extruders 26. Each extruder has a tapering barrel 28, a fish-tail nozzle 30 and a feed hopper 32. In the barrel of each extruder is arranged a tapering Archimedean screw 34 driven by a motor 36 connected by a belt 38 to a shaft 40. Two worms 42 on the shaft 4!! engage with worm wheels 44 on the ends of the screws 34.

The peat to be de-watered isfed into the hoppers 34 and is forced through the extruders by the screws 34. The cross sectional area of the outlet of the nozzle of the extruders is about the same as that of the barrels at the smaller end and, therefore, the peat is not highly compressed. The main object of the extruders is to present the peat to the rollers I2 and IE to the best advantage. Some water will be squeezed out of the peat in the extruders and this is evacuated through slots 46 in the barrels 2B.

The fish tail shape of the nozzles 30 causes the peat to be presented to the rollers l2 and [6 as fairly wide ribbons. These ribbons are then squeezed by the rollers and are thus spread out over the whole of the length of the rollers as indicated by the dotted lines 48 in Figure 2.

The peat is prevented from spreading beyond the ends of the rollers by flanges 50 on the roller [2.

It will be seen from Figure 1 that the roller I6 is set with its axis a little in front of that of the roller l2 and that the extruder nozzle 30 is set a little below the nip of the rollers. This ensures that the ribbon-of peat is fed slightly upwards to the nip and that the Water expressed from it by the rollers can run backwards on the roller l6 out of contact with the peat. To assist further in the evacuation of the expressed water, the surface of the lower roller I8 is made as smooth as possible. The surface of the upper roller is, however, roughened as, for example, by sand blasting, as this has a tendency to cause the peat to adhere to it. This tendencyis increased if the temperature of the upper roller is maintained above that of the lower roller and, therefore, the upper roller is provided with a hollowshaft 52 connected by a pipe 54 to a source of steam (not shown). Steam at about 30 lbs/sq. in. is preferably used.

The longer the peat remains on the heated roller I-Z, the more moisture will be evaporated from it. There is, therefore, advantage in using aroller of large diameter, say 24 inches or more. The use of large rollers also has the advantage of applying the pressure to the peat gradually.

In the machine shown in Figure l, the peat passes'right over the roller 12 and is finally taken oif by a scraper 58 which is pivotally mounted on a trough 58 containing an Archmedean screw 60 driven by means notshown. The dewatered peat which, by the time it reaches the trough 58, is in a crumbly condition, is further broken up by the screw 50 and is delivered to the collecting points. The speed of the rollers is preferably made variable so that the length of time during which the peat remains on the heated roller can be varied. A suitable speed for the roller 12, is in general, -revs. per min.

The machine shown in Figure 3 dilfers from that shown in Figure 1 only in that the peat is kept in contact with the upper roller I2 for a shorter time. The peat is removed from the roller by an adjustable scraper 82 and deposited on a conveyor 64 which moves beneath a number of tially.horizontahmeans for feeding the peat substantially horizontally to and through said nozzle, a lower roller, hollow upper roller forming a horizontal nip with said lower roller at a level slightly below that of the highest point in said lower roller, means for driving said rollers and means for passing steam through said hollow upper roller, said nozzle being disposed out of contact at least with said'lower roller and being so disposed relatively to said nip that the peat issuing from said nozzle travels to said nip out of contact with said lower roller.

DUDLEY SEATON KING.

BEEE'BJENCES CITED The following references are of record'in the file of this patent:

UNITED STATES PATENTS Number Name Date 785,600 Ekenberg Mar. 21, 1905 860,342 Taylor July 16, 1907 1,037,545 Savy Sept. 3, 1912 1,408,827 Prescott Mar. 7, 1922 1,481,410 .Brien Jan. 22, 1924 2,068,181 Hurxthal Jan. 19, 1937 2,281,184 Dykstra et a1. Apr. 28, 1942 FOREIGN PATENTS Number Country Date 202,793 Great Britain Aug. 30, 1923 Great Britain Feb. 6, 1930 

